Figure 1

Comparison of methods currently used for counting oocysts. (A) In the formalin fixation method, the midgut was opened as a single layered specimen that avoided the overlapping of oocysts. However, unstained oocysts were indistinct and difficult to distinguish from insect tissue. (B) On the other hand, the mercurochrome staining method made the oocysts distinct from the surrounding tissue, although the two layers of oocysts overlapped and they were difficult to distinguish from each other. (C) In the improved technique, the red-stained oocysts could be distinguished clearly from the insect tissue, and in the single layered specimen they were no longer overlapping each other. Arrows indicate oocysts in the midgut of A. stephensi at 12-14 days post-feeding of P. berghei ANKA strain infected mice.